Mini Laser Light Show on an 08M2

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BobMcNobby

Senior Member
Hi All,

As a continuation my my recent development on DMX lighting projects (which are going full swing) I have started work on a 08M2 based laser light show.

Note : I understand the risks involved with working/demonstrating lasers, and been reading the H&S details

The light show PCB will be small, and I mean SMALL ! and will probably fit into a matchbox-sized box (40 x 50) excluding batteries
I shall be powering a 3-5mw red laser and driving two tiny motors (with wobbly mirrors) from the 08
There will also be a sound input which I shall derrive beat speed and ambient volume from to drive laser sequences
all the above will be fitted to the 40x50 pcb

All parts will total less than 10GBP

I intend to deliver 1m diameter light shows at 5m distance

Once this is up and running I shall post details/code/photos etc

This is a very exciting project for me

Regards Bob
 
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SAborn

Senior Member
Jaycar use to sell a laser kit with 2 motors and mirrors all included, that might make the project easier.
I think you guys have a jaycar in the UK so might be worth a look.
 
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BobMcNobby

Senior Member
Thanks SABorn, I have seen this, but I really wanted to try something much much smaller and controlled by a micro
The 08m2 is perfect for this, I know it only has one PWM but I will be creating my own PWM outputs (2 off) in software with the 08 running at 32mhz this shouldnt be too much problem. Regards
 
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Dicky Mint

Senior Member
Hi Bob

That sounds an interesting project.

I expect you'll need to employ SMD components to fit your ambient sound monitor, beat speed measurer and mirror motor drivers on the same 40x50mm board.

Definitely doable though I expect it will need a lot of setting up.

I suppose what you will need is a fairly straightforward microphone and preamp circuit feeding an ADC on the PICAXE and output to revolve the mirror motors after some numerical manipulation.

DM
 
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BobMcNobby

Senior Member
Also, the motors dont need to be very big, only low torque required. I shall be spinning 10mm & 15mm diameter acrylic mirrors which weigh (and cost) next to nothing. The motors are also very cheap and measure 12mm x 6mm diameter !
 
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SAborn

Senior Member
Fair enough.

Maybe the micro motors like is used in mobile phones for the vibrator (or the brissle bot) would make a miniture setup.
Its not to hard to get ones paws on a few redundant mobiles now days, and the nokia phones have good little motors.
 
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BobMcNobby

Senior Member
Hi Dicky, I think I can fit a standard 08 on the board and a small condenser mic, they fit around the motor and laser diode.
I am going to try and do the beat/ambient monitoring using a passive RC filter into ADC and "average vs transient" voltage monitoring to extract the beat.
The maths for all this will probably be derrived from my other project (sound to full DMX conversion), its quite a cool way of beat locking and works a treat at 64mhz on a 28x2
 
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BobMcNobby

Senior Member
Hi SABorn, exactly that, infact the motors I have coming (and already have) are those type. I have some virbrating ones but the weights will be impossible to remove without bending the 0.4mm shaft, I have ordered some from germany :mad:)
 
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SAborn

Senior Member
I think if you heated the weight with a butane flame they would pop off the shaft, but i have not tried it.

Or use the vibration to your avantage and have it hover around like the brissle bots do.
 
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Dicky Mint

Senior Member
OK that sounds good. You'll probably need some amplification for the condenser mic though, perhaps a simple, one or two stage small signal transistor amp?
 
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BobMcNobby

Senior Member
SABorn, I was actually considering using 2 vibrating motors 90 degrees apart to vibrate a mirror suspended on a balloon/condom, very simple & neat idea !! lol

DM, I shall try both amplified and non-amplified versions, I am thinking that I dont actually need much signal/resolution to get the info I need out of the sound. I have a quad opamp solution on my other board which works a treat (dual LP filter @ 100hz into an averaging comparator) - cheers
 
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SAborn

Senior Member
Adding a condom to the project bring all sorts of comments to mind and then the fact of the vibrator too............well lets just say, i could not find a way to express the thoughts on a public forum, othen then it might become a right stuff up.;)

Although a laser guided vibrating condom with sound activation could be a dangerous thing, dont bend over to pick up your screwdriver.:eek:
 
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BobMcNobby

Senior Member
I have a pretty good sense of humour and witt, and I cant believe I missed the potential joke in what I had written !! ha ha (well done for spotting that !)
 
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Dicky Mint

Senior Member
Silly perhaps but I've just not thought of using a electret condenser mic to output to an ADC pin on a PICAXE, I like the idea though! Simple things please simple minds and I shan't comment on the vibrating condoms except to ask are you thinking of filling the condom with Helium to elevate it?
 
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BobMcNobby

Senior Member
DM, if the program loop is very fast you can read low frequency input, then average its peaks in software, I use 8, 16 & 32 bucket averaging as they are easy to manipulate. I am sure that by comparing a 32 bucket average to an 8 bucket average this will result in detecting (somewhat) when low frequency (100hz ish) peaks are found. Its kind of how I do it in hardware with opamps/caps/res, but this way it could get rid of heaps of components and get the 08 to do all the hard work... lol, I wasnt going to inflate the condom/balloon I was just going to suspend it across a square gap in the pcb and put the mirror on the middle :mad:)
 
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Dicky Mint

Senior Member
Sorry I'm a beginner, bucket averaging is..?

I think I see your plan to vibrate a mirror or a pair of mirrors at 90 degrees with their centre points directing the laser light at the middle of the display pattern. The elastic properties of rubber centring the display and being sufficiently elastic to create the sound to light pattern display.

I'm interested in this idea from two points of view, first the detection of ambient sound using just a PICAXE and an electret mic and and the light display depending on that sound amplitude and beat..

I'll certainly look into bucket averaging but if you could give me any pointers they would be valuable I'm sure!

DM
 
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BobMcNobby

Senior Member
Bucket averaging is basically, remembering a series of number to average with, and you imagine someone passing the numbers down the line like people passing buckets (not very great explaination !)

example

peek 101, val1
peek 102, val2
poke 101, val2
peek 103, val3
poke 102, val3
poke 103, newVal
w1 = val1 + val2 + val3 + newVal ' average add
average = w1 >> 2 ' divide by 4

you could use peek/poke if you have many buckets, or actual variables if you need only a few buckets

I am also considering using peizo sounders to create XY vibration/movement

I will let you know how I get one with monitoring the ambient sound and beat detection as they need two completely different algorithms to obtain the info

Bob
 
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Dicky Mint

Senior Member
Hi e

S151 books I'm afraid went there own way a few years ago.

I think it did probably cover this but under the general heading Statistics, which, I'm sad to say, I managed to eliminate from my study of maths almost without trace!

I'm afraid I don't really get it from Wikki either but I get the word 'algorithm' and it brings fear to the heart!

Rick
 
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eclectic

Moderator
OK, how about a postie's sort?

A very long street.
Divide the house numbers into blocks of tens.
All the letters for 1 - 10 in one red elastic band. (Brit joke)
11-20 in another
21-30 in another.......... and so on.

And then sort each band 1 - 10

e
 
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Dicky Mint

Senior Member
So each band when divided by the number of houses in that band gives the average number of letters of each house in that band. Or the number of letters in band 1 or 2 or 3 is proportional to the average no. of letters per house. I think I get the analogy thus far.
 
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AndyGadget

Senior Member
bobmcnobby2 said:
I have some virbrating ones but the weights will be impossible to remove without bending the 0.4mm shaft, I have ordered some from germany :mad:)
Click to expand...
If they're the split type of weight, I've got them off by using needle-nose pliers slightly open against the flats and then tightened in a mini-vice.
It's fiddly but it opens up the gap and the motor drops out.

Andy.
 
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BobMcNobby

Senior Member
After a short delay waiting for parts to come in, I now have working hardware for the laser light show
So far I have managed 1m wide patterns at 3m with dual mini motors and 10mm dia mirrors

The board is currently measuring a mere 35mm x 45mm !!!
There is room left for micro, programming socket, dual opamp, electret mic and some R's & C's

The basic sound-to-light electronics and software will start tommorow

I have attached a picture of my efforts so far (rather fiddly, but soooo worth it !)
 

Attachments

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Dicky Mint

Senior Member
Hi bob, that's genius mate I'm well impressed!

All put together on stripboard too!

A photo of the light show would be good!

I really hope your sound-to-light works as well as this.

DM
 
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BobMcNobby

Senior Member
Cheers Dicky, I may have to video it and stick it on youtube, lasers look better with heaps of fog rather than what is projected on the wall
I have tried to video foggy-lasers with my phone and it looks pants, its one of those "you gotta be there" moments !!

The hardest job for me was centralising & fixing the 10mm mirrors accurately onto the 0.4mm shafts !!

Strip board is the future man !! whoever thought it up was a genius !! lol

Regards Bob
 
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BobMcNobby

Senior Member
Actually the stripboard was really handy, as it gave me accurate positions to aline the laser and motors up
laser needs to be exactly 45 degrees to first mirror and central to its face, the second mirror needs to be at 180 to first but positioned so that the beam path is 90 degrees

The pitch of the holes in the Vero was perfect for this

Also, the DIL sockets were a perfect mount for the motors to give height above the PCB for the mirrors
and I found the perfect holder for the Laser.... the inside of a cheap fuse holder !!

:)
 
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Dicky Mint

Senior Member
Hi bob

Sounds to me like serendipity! When things just go together regardless!

I'd really like to see it working

I might even try to build one though probably the other side of Christmas now
 
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BobMcNobby

Senior Member
Go for it Dicky, I will try and iron out all the bugs first, then I will post the code and layout etc

I decided that my mirrors eeded to be really accurately positioned on the motors, if they are off center the speed is not consistent
therefore it was time to make a little gluing jig to position them accurately, see attached

Bob
 

Attachments

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BobMcNobby

Senior Member
Thats a pretty cool substance sir, I have seen similar but never used it, I may get some
The mirrors do need to be well fixed to the shaft, I used araldite epoxy resin

The mirrors are only 10mm in diameter and my jig above works really well
I put a couple of mm of domed resin on the back of the mirror, put it in place then slide the motor down into it till the shaft touches the mirror backing

Regards
 
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moninos

New Member
Pager motor. After destroyibg a few, trying to remove the weight by -pulling - heating - pushing - grinding, I finaly found the foolproof method:
Simply crush the weight in a wise. It is made of a weaker alloy than the steel shaft and will crush under high pressure without affection the shaft.
 
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BobMcNobby

Senior Member
Cheers for that Eclectic, I didnt realise how much stuff was in the store here !! (must be more observant, me !)

I had the same problem Moninos, after a whole load of yanking and prizing they came off. I got ones without weights now
 
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Jamster

Senior Member
I got chance to use a laser disco light yesterday in my the schools production: We Will Rock You, unfortunatly the "sound tracking" functions (that were meant to home it in on a stomp by a member of cast) didn't work and our laser cage turned out as a laser dot...

I hope you have much more luck than we did and may be building a similar project using some of your ideas :)
Jamster
 
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peterzomer

New Member
Hi Guys,

If i'm right this project is about (continues) rotating motors which will produce the same images all the time.

I worked for quite some years in the laser industry and we used so called galvo's.
In fact they are just very small stepper motors with a mirror on it, positioned 90' from each other.
In this way you can create a X-Y grid and project real pictures on a wall and even make animations!

The steppes diameter are around 15mm and 15mm long.
We never thought about using the PIC to control them.

Is someone is interested in these parts, please let me know and I will post some pictures here.

Gtz,
Peter
 
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SAborn

Senior Member
@peter it would be of interest to see some pictures, were the mirrors themselves also on an angle to the motor shaft.
 
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